posted on Dec, 15 2005 @ 12:51 PM
I know it's a difficult concept to understand, but just because the galaxies are flying away from each other (at least, most outside of our "Local
Group") - does not mean that they are actually moving away.
In fact, from the view of someone in that galactic cluster, it would look like ALL other galaxies are moving away from them. The same goes for all
other galactic clusters.
Like I said, this is because space-time is expanding. The distances between galaxies are growing not because they are moving, but because the area
between them is growing.
Imagine this. You have a water mattress, where the rubber on it can expand infinitely. Now, place some bowling balls on the mattress, and start
pumping water into them. The bowling balls won't start moving, but they'll make dents in the mattress. In fact, the distance (from your point of
view) is that the bowling balls aren't moving, and are staying exactly where they started.
However, if you were to measure the distance to each bowling ball by putting a tape-measure across the surface of the ever-expanding bed, you would
find that the 2-dimensional distance between the bowling balls is increasing!
Now, let's make this more "universal" and more to the point with the speed of light. Let's say you made this mattress absolutely MASSIVE! And you
also place a bunch more bowling balls on it. If you could fill it up with water at the same speed as before (so the expansion of the mattress takes
place at the same pace), then you would find more interesting things.
The further away a bowling ball was from another bowling ball, the faster the 2-dimensional distance between them would increase (as there's more
room for more water, which means more expansion). If the mattress was large enough, it would actually seem like the 2-d distance between them would,
eventually, be growing at past the speed of light! This is because the expansion of each individual piece of space on the mattress is happening the
same everywhere, it's not flowing out from a specific place.
Now, take everything I just told you, and move it up 1 dimension. 3-dimensionally the galaxies appear to be moving away from each other at an ever
increasing pace (and at really far away galaxies, at more than the speed of light). Perhaps 4-dimensionally they are not, and if we could "pick them
up" off the mattress, and then move them, they would appear to move faster than light, even though they're just skipping all the curves in space
Do you understand now?